A method for controlling a combustion process in a gas turbine wherein a combustion chamber, a control device storing a calculation model of the combustion process, and an exhaust air measurement device are used. A permissible limit value for nitrogen oxides and for carbon monoxide as pollutants is set. The actual value of at least one of the two pollutants is measured continuously in the exhaust air. When a signal to reduce the power of the gas turbine to a lowest possible value is given, then a minimum fuel supply at which the limit values are complied with is calculated. The fuel supply is then reduced either until the calculated minimum fuel supply is reached or until the continuously measured proportion of the pollutant reaches the permissible limit value.

A method of mitigating contrails produced by an aircraft having a set of gas turbine engines, comprises the steps of (i) for each engine in a first subset of the engines, reducing the operating efficiency of the engine to produce a reduction in thrust provided by that engine and (ii) for each engine in a second subset, increasing the fuel flow to the engine to increase the thrust provided by that engine, the set of at least two gas turbine engines consisting of the first and second subsets. The method provides for contrail mitigation action by means of engine operating efficiency reduction to be directed to a first subset of engines for which contrail mitigation per unit engine operating efficiency reduction is greatest, the resulting reduction in thrust provided by such engines being at least partially compensated by increasing fuel flow to engines of the second subset.

An acquisition unit is configured to acquire measurement values of a target device. The measurement values that are acquired include at least a temperature and a flow rate of an input fluid to be input to the target device, and a temperature and a flow rate of an output fluid to be output from the target device. A correction unit is configured to obtain a correction measurement value by which the measurement values are corrected through thermal equilibrium calculations based on the measurement values. A distance calculation unit is configured to calculate a Mahalanobis distance with a factor of the correction measurement value.

A method is provided during which an aircraft powerplant is provided. The aircraft powerplant includes a combustor and a water recovery system. The water recovery system includes a condenser and a reservoir. Fuel is combusted within the combustor to provide combustion products. Water is extracted from the combustion products using the condenser. The water recovery system is operated in one of a plurality of modes based on likelihood of contrail formation. The modes include a first mode and a second mode, where the water is collected within the reservoir during the first mode, and where the water passes through the water recovery system during the second mode.

A method, system and apparatus are provided for reducing or eliminating contrails formed by an aircraft as it travels through the sky, and more particularly, to disrupting formation of contrails and altering the electromagnetic properties of already-formed contrails through use of one or more lasers. Methods include: positioning at least one laser such that at least one beam from the at least one laser is directed to a position at which contrails form aft of a wing of the aircraft; detecting contrail formation in the position at which contrails form aft of the wing of the aircraft; activating the at least one laser source in response to detecting contrail formation; and reducing or eliminating the contrail in response to activating the at least one laser source.

A turbine device includes a fluid compressing device compressing a fluid, a combustion device, a fuel supply device supplying a fuel to the combustion device, the combustion device combusting a mixture of the fluid and the fuel, a sensing device, and a control device. The sensing device senses a humidity of the fluid compressed in the fluid compressing device. The control device controls the supply of the fuel by the fuel supply device based on the humidity sensed by the sensing device.

An aircraft propulsion system includes a hydrocarbon fuel store, a hydrogen fuel store, an engine system capable of producing thrust by combusting hydrocarbon fuel and/or combusting or oxidising hydrogen fuel, a conveying system to convey hydrocarbon and hydrogen fuel from the fuel stores to the engine system and a control system to control the respective flow rates of the fuel within the conveying system. The control system adapts the fractions of the total fuel energy flow rate to the engine system represented by the hydrocarbon and hydrogen fuel energy flow rates in order to reduce climate warming impact caused by at least one of carbon dioxide, water vapour and condensation trails and/or increase climate cooling impact caused by condensation trails produced by the aircraft propulsion system compared to a dual-fuel propulsion system in which a reserve of hydrocarbon fuel is entirely combusted before any of a reserve of hydrogen fuel.

An aircraft including lean-burn gas turbine engines operating in pilot-plus-mains mode with a given initial fuel flow W.sub.0, a method of controlling the optical depth of contrails produced by a first group of engines includes the steps of (i) reducing fuel flow to each engine in the first group to change the operation of each engine from pilot-plus-mains mode to pilot-only mode, and (ii) adjusting fuel flow to one or more engines in a second group of engines such that the total fuel flow to engines of the second group is increased, all engines of the second group remaining in pilot-plus-mains mode, and wherein the set of lean-burn engines consists of the first and second groups. Depending on atmospheric conditions, the average optical depth of contrails produced by the engines may be enhanced or reduced compared to when all engines operate in pilot-plus-mains mode with a fuel flow W.sub.0.

A condensation irradiation system is disclosed comprising an electromagnetic radiation emitter mounted on a locating structure, the locating structure being arranged in use to position the radiation emitter so as radiation emitted therefrom travels through a condensation detection region adjacent an upstream side of a gas turbine engine fan.

This invention concerns an aircraft propulsion system in which an engine has an engine core comprising a compressor, a combustor and a turbine driven by a flow of combustion products of the combustor. At least one propulsive fan generates a mass flow of air to propel the aircraft. An electrical energy store is provided on board the aircraft. At least one electric motor is arranged to drive the propulsive fan and the engine core compressor. A controller controls the at least one electric motor to mitigate the creation of a contrail caused by the engine combustion products by altering the ratio of the mass flow of air by the propulsive fan to the flow of combustion products of the combustor. The at least one electric motor is controlled so as to selectively drive both the propulsive fan and engine core compressor.